Avoid redundancy. If someone has already defined a name that does roughly what you want, please reuse it.

Be sure to include all the itemsoutlined in the specincluding a link to a specification that specifies the keyword as an HTML meta keyword. If a proposal lacks a specification and a version in a complete specification exists, the latter is to be preferred.

Alphabetize by keyword, without regard for case, in any table. Sort nonalphanumerics by ASCII value.

Namespaces cannot be reserved. Instead, register individual names (known as enumerated values although you don't have to number them).

URL-valued attributes must not be added to this page as meta names but should be registered as rel keywords instead.

forces iPhone Fullscreen mode, if added to home screen. Not needed anymore.

No specification yet

Proposal

application-name

For Windows 7: "[D]efines the name of the Pinned site application instance. This is the name that appears in a tooltip when hovering over the Pinned site button on the Windows 7 taskbar. The application name is also appended to the window title of the Pinned site application instance." Although the documentation refers to an application, it gives an example of writing this metadata for HTML. Indeed, this name must not be used except in a Web application, according to HTML Living Standard and HTML 5.1.

Checks whether Blazerr SEO has been used or not. It contains the user-id and the SEO Version.

Usage: <meta name="blazerr-seo" content="0001;v0.7">0001 is an example for a user id, v0.7 identifies which version of SEO is used (In this case version Beta 7 / 0.7). If you're using Blazerr SEO, you have to include this meta-tag. Otherwise the tool will not work.

Used to identify users for JokeNetwork's Blazerr Support-System along with a cookie. The verification of a user without the use of cookies can be obtained with the deprecated meta tag blazerr-support-id-noncookies.

To replace the obsolete dc:collection. A collection is described as a group, an aggregation of topics Used to describe the top-level content of XHTML documents. These appear in your META tags showing a group of subject. Website Taxonomy improve classification for search engine analysis and semantic communication with a description language content.

Defines the vendor's contact information by way of a phone-number (such as the customer support number), an e-mail ID (such as the customer support mail ID) or a physical address (such as the office address or billing address).

Usage: <meta name="contact" content="+1-555-555-5555 abc@xyz.com '5844 South Oak Street, Chicago, Illinois'">or in case of multiple entries:<meta name="contact" content="Chicago: +1-555-555-5555 abc@xyz.com '5844 South Oak Street, Chicago, Illinois'; Brookfield: +1-444-444-4444 def@xyz.com '2341 Cherry Lane, Brookfield, Illinois'">
The content attribute is a space separated string containing the phone-number followed by the e-mail ID and then the address (specified within quotes).
For specifying multiple entries a semi-colon separated list of name: value pairs can be defined. The name can be any descriptive tag identifying the given location.Valid phone numbers and mail IDs should be provided by the vendor. The address can either be a string specified within quotes or the latitude and longtitude coordinates.

This defines an error code web page so that Webtrends can identify it as a non-success page. Generally used to identify pages that contain 400 and 500 series return codes. As a result, Webtrends excludes these pages from its standard "Pages" report, to instead populate its standard "errors" report.
Example:

Used by the Detectify web vulnerability scanner as a domain verification key. The Detectify service will only consider the domain authenticated if it contains the "detectify-verification" meta tag, with the content set according to a per-customer token.

National subdivision (state, canton, region, province, prefecture) of civil address to which the page is related. For resources within the US and Canada, corresponds to the common 2-character State/Province codes.

Used to declare text that should not be translated by the Google Translate plugin (<meta name="google" value="notranslate"> will declare the whole page should not be translated, while <span class="notranslate"> is for text or paragraph areas you wish to not be translated.

Used "[t]o tell Google not to show a Sitelinks search box when your site appears in the search results" (implement with content="nositelinkssearchbox") (already in use).

Presumably, multiple meta elements named "google" should all be parsed but this is may not have been explicitly specified anywhere.

A point or period of time associated with an event in the lifecycle of the resource represented in terms of an ICAS date and time format of unspecified information density (may include full, long, medium, short, or compressed forms).

a preliminary specification in the aaticas group on LinkedIn (http://www.linkedin.com/groups/aaticas-4034149). after a period of review, a specification for AAT ICAS meta keywords for HTML(5) will be referenced on an AAT ICAS area of the aatideas.org web site.

Proposal

icas.datetime.abbr

A point or period of time associated with an event in the lifecycle of the resource represented in terms of an ICAS abbreviated format such as "d2M03 t969".

a preliminary specification in the aaticas group on LinkedIn (http://www.linkedin.com/groups/aaticas-4034149). after a period of review, a specification for AAT ICAS meta keywords for HTML(5) will be referenced on an AAT ICAS area of the aatideas.org web site.

Proposal

icas.datetime.day

A point or period of time associated with an event in the lifecycle of the resource represented in terms of ICAS day-of-year format such as "2012 day 333 t969".

a preliminary specification in the aaticas group on LinkedIn (http://www.linkedin.com/groups/aaticas-4034149). after a period of review, a specification for AAT ICAS meta keywords for HTML(5) will be referenced on an AAT ICAS area of the aatideas.org web site.

Proposal

icas.datetime.long

A point or period of time associated with an event in the lifecycle of the resource represented in terms of ICAS long date format such as "UCN 12012 M03 Blue ❀ day 333 ❀ IDC zone(UT) t969 tt189". example <meta name="icas.datetime.long" content="UCN 12012 M03 Blue ❀ day 333 ❀ IDC zone(UT) t969 tt189"/>

a preliminary specification in the aaticas group on LinkedIn (http://www.linkedin.com/groups/aaticas-4034149). after a period of review, a specification for AAT ICAS meta keywords for HTML(5) will be referenced on an AAT ICAS area of the aatideas.org web site.

Proposal

icbm

Defines geographic position to which page is related to. The acronym stands for ICBM Intercontinental Ballistic Missile - an old, humorous allusion to the possible use of such coordinates.Example:

If set to "true", disables Internet Explorer 11 Reading View button adjacent to address bar when the page is detected to have content suitable for Reading View. This is intended for pages that are not articles and are not intended to be read in IE 11 Reading View.

Like keywords but instead keywords-not support Boolean NOT searches; useful for metaphors, satire/parody, and pages that say "this page is not about subject x" which therefore would be erroneously excluded by a NOT search against x.

Specifies the cryptocurrency address (bitcoin, etc.) for sending tips to the people responsible for creating this page's content. This tag is used by various browser plugins that want to compensate the site's creators. Since it's microtipping instead of micropayments, there is no need to specify an amount.

Specifies the mobile-compatible url of the web page. Used by mobile browsers and search engines to redirect mobile phone visitors to the proper mobile page.

The following properties can be used in the value of the content attribute:url - The mobile-compatible url of the web page.format - The format of the mobile page. An enum of "wml", "xhtml" and "html5".Example:

The "msapplication-config" metadata defines the path to a browser configuration file, letting you set pinned sites customizations (such as tile background, badge updates and notifications) with this external XML file rather than metadata within the HTML markup of webpages.

<meta name="msapplication-config" content="IEconfig.xml" />

Note
Without this metadata, IE11 looks for a default "browserconfig.xml" in the root directory of the server.

The "msapplication-starturl" metadata contains the root URL of the application. The start URL can be fully qualified, or relative to the current document. Only HTTP and HTTPS protocols are allowed. If this element is missing, the address of the current page is used instead.

Jump List items act as entry points into the website even when the browser is not running. A Jump List can contain commonly used destinations and tasks. Some items apply to the whole site, and some apply only to specific users.
For example, to add a single task called "Check Order Status" specify a meta element in the head of your webpage, as follows:

The "msapplication-TileColor" metadata define the background color of a tile in Pinned Sites in Windows 8. The tile color can be specified as a hex RGB color using CSS’s #rrggbb notation, via CSS color names, or by the CSS rgb() function.

The "msapplication-window" metadata sets the initial size of the Pinned Site window when it is launched for the first time. However, if the user adjusts the size of the window, the Pinned Site retains the new dimensions when it is launched again.
The following properties can be used in the value of the content attribute:

Prevent a Microsoft browser from adding a certain kind of content to a page because users could be confused into thinking the added content was part of the original page. (It's likely only relatively few copies of the browser, a beta release never finalized, are still in the installed Win base, but the base is so large that even relatively few would still be a significant absolute quantity.)

This tag is used by Google: Custom Search Help: Meta Tags, as accessed 1-8-16. And "<meta content='true' name='MSSmartTagsPreventParsing'/>" appeared (with internal quote marks as singles) in the source code for <[9]>, as accessed 4-27-09.

To reduce the "fake news" problem, this lets well-meaning page authors label satire and parody appropriately in metatags although unlabeled in content (not explicitly labeling being common in satire and parody). Characterize the principal content of the page as nonfiction, fiction, mixed, or other. This way, other websites and users needn't be fooled.

When a page uploaded two or more times with the same last-modification date (per dc.modified, dcterms.modified, or article:modified_time metatag), distinguishing different uploads even on the same date can be done with the page-version metatag.

Used by Pingdom monitoring services as a heartbeat verification. The heartbeat service will only consider the request successful if it contains the "pingdom" meta tag, with the content set according to a per-customer key.

Signify an authority, subject to search engine's or directory's judgment of importance and credibility (the judgment could be by a human working for a search engine), so the authority's listing of experts can carry weight, making search results more useful.

The Restricted to Adults label (RTA) provides a way for adult oriented websites to indicate that their content is off limits to children. RTA was introduced in 2006 and is currently used by a large number of adult web content providers. RTA is recognized by all major parental control filters.

revisit-after is used to tell search engines how often to recrawl the page. To our knowledge only one search engine has ever supported it, and that search engine was never widely used — at this point, it is nothing more than a good luck charm.

The purpose is to enable search engines and other cataloging services to compile the types of rights allocated to the work. (Does any search engine actually implement this? hsivonen 07:34, 14 July 2011 (UTC))

This keyword does not provide, remove or alter any legal protections or designations.

A comma-separated list of operators explaining how search engine crawlers should treat the content. This meta name is already supported by every popular search engine.Possible values are "noarchive" to prevent cached versions, "noindex" to prevent indexing, and "nofollow" works as the link rel value with the same name.The content value "NOODP" has been offered elsewhere, so I'm proposing it here. It blocks robots from using Open Directory Project descriptions of a website instead of Web pages' own meta descriptions. It may have been introduced by Microsoft.The content value "NOYDIR" has been offered by Yahoo, so I'm proposing it here. It blocks Yahoo's robot from using the Yahoo directory's descriptions of a website instead of Web pages' own meta descriptions. Whether any other robot supports this is unknown but possibly no other search engine uses Yahoo's directory anyway.

Prevents the Skype browser extension from automatically seeking through the page and replacing telephone numbers (or any number the program's algorithm thinks is a telephone number) with its own custom presentation that allows direct invocation of the Skype program to call the telephone number.

Where another metatag provides a subject for the page, that subject should be selected in accordance with a standard system for classifying subjects, such as one used for academic or public libraries of books. This metatag identifies the system in use for the current page, using a standard controlled vocabulary of system identifiiers.

(Note: This violates HTML5, section 4.2.5.2, which says this, because the value is a URL, must be a link element and not a meta element, but Google already recommends and parses this as a meta element.)

Provides a way for documents to specify (using markup rather than CSS) the size, zoom factor, and orientation of the viewport that is used as the base for the document's initial containing block. The following properties can be used in the value of the content attribute:

When a visitor to your site clicks on an ad, that action is referred to as an Ad Click. The following META tag tracks advertising clicks:

<META NAME="WT.ac" CONTENT="name">

Defines the name of the advertisement clicked to reach a particular web page. The Ad Click must contain an external redirect back to the client. The redirect needs to include the necessary code to generate a hit to the SDC server. You can designate multiple Advertising Clicks using semicolons.
Examples:

The name of the advertisement clicked to reach a particular web page. To capture this information with DCS, the Advertising Click must contain an external redirect back to the client. The redirect needs to

include the necessary code to generate a hit to the DCS. The maximum length for each name is 64 bytes.

Visitors often view advertisements that they do not necessarily click on. You can use On-Site Advertising to determine the number of visitors to your web site who view particular ads. With this feature you can produce advertising reports for each of your clients.
If you are selling advertising space on your web site, for example, you can collect traffic statistics to help determine pricing schedules.
The following META tag tracks advertising views:

<meta name="WT.ad" content="My content">

An Ad View occurs when a visitor views a page containing an ad. An ad is a link or graphic that contains an Ad Click parameter in the query portion of it's URL.

Used to configure the appropriate Webtrends advanced feature. These are just some of the more popular ones. These appear in your META tags. – showing you the web page, the source (meta tag), the log files entry and the subsequent WT report.
Example:

Used to configure the appropriate Webtrends advanced feature. These are just some of the more popular ones. These appear in your META tags. – showing you the web page, the source (meta tag), the log files entry and the subsequent WT report.
Example:

To attract new students, a university launches a marketing campaign by sending recruitment email to all graduating high school seniors in a metropolitan area. The email links to a special landing page in the university’s web site, containing the following META tag to track marketing campaigns.
Example:

This defines a scenario step name for the page or set of pages to be included in the scenario. This in turn produces a funnel type report in Webtrends. It works when paired with metedata tag name WT.si_n.
Example:

This defines a scenario step number for the page or set of pages to be included in the scenario. This in turn produces a funnel type report in Webtrends. It works when paired with metedata tag name WT.si_n, and as an alternative to Wt.si_p.
Example:

If your site is hosted on multiple servers, a server cluster, or a server farm, and you want to evaluate the performance of your load balancer, Webtrends can track page views for each server. To do so, populate the following META tag on all pages on each server:
Example:

<meta name="WT.sv" content="My Server">

Defines the name of the machine that serves the web page. If you have two servers (Server1 and Server2), you would make two copies of the META tag and designate CONTENT=“Server1” for deployment to pages on the first server and CONTENT=“Server2” for deployment to the same pages on the second server.
For a server farm, you can extract the value of the built-in server name and dynamically assign it to the
META tag using server-side scripting.
Example:

You may want to modify a page title before sending it to Webtrends in the following cases:

You are dealing with dynamic content pages identified by URL parameters, and the page title represents the title of the base URL page rather than the dynamic content page.

Unless you modify the page titles, all pages have the same title in the reports.

All pages have been assigned the same title, for reasons of style or company policy.

Even though URLs are displayed in addition to page title, the entire URL cannot be depended upon to distinguish one page from another.
Use server-side scripts to change the title to something that reflects the content of the pages so that you can identify them in reports. Next, pass the customized page titles to Webtrends, using the following META tag:

The datetime at which the document was created. The value is an ISO8601 date. The date MUST follow the W3C Profile of ISO 8601 with a granularity of "Complete date:" or finer. The BBC use this name.

Incomplete proposal

Lacks link to a spec

dir-content-pointer

This is no longer useful. The function is better performed with HTML markup, some of which may be newer than this meta name.When several pages in a directory include main content, a table of contents, an index, and the like, a search engine may be able to organize results more usefully by identifying which is which with a standard vocabulary, helpful when different publishers use different conventions when displaying or printing content.A value is free-form case-insensitive text without a comma and optionally with a trailing number. Multiple values are to be comma-separated (multiple values are appropriate when one document serves multiple purposes). Singular and plural forms have the same meaning.Recognized values, which are pointer types to which numbers may be suffixed, are limited to "start" meaning 'the first page that should be seen by a user' (this may be anywhere in the directory and anywhere within content), "toc" meaning 'table of contents', "intro" including introductions, forewords, prefaces, and tables of figures, "abstract", "main", "bibliography" and "biblio", which have the same meaning, "index" which may mean 'sitemap' or not, "afterword" and "update" which have the same meaning and need not actually update, "credit" meaning 'credits and acknowledgments', and "author bio" meaning 'author's biography', including any information about the author including credentials and contact information. The number suffix may be spaceless or not.When numbers are suffixed, a search engine or directory should arrange like items in numerical order in the results, with unnumbered items following like items that are numbered, e.g., intro 1, intro 2, main 1, main 2, main, main, and so on.Each directory and each subdirectory has its own sequence.

Incomplete proposal

Lacks link to a spec

expires

meta name='expires' defines the expiration date of the page. This can be used for web pages in preparation for an upcoming event, e.g. a registration form for an exposition or competition, or other cases with a pre-set date when the document will no longer be valid, e.g. a product offer in a special sale or a support page for a product known not to be supported anymore from a given time onward.

Search engines should respond to this meta tag in a reasonable way, i.e. by removing the page from their main search results after the expiration date (possibly still returning the result in a special search for expired pages as long as the page exists and is not explicitly excluded via robots.txt or meta name='robots' etc.) or simply by indicating to the user that this result is out-of-date.

The content attribute should define the expiration date in accordance with http://www.w3.org/TR/NOTE-datetime . The meta tag should not be used for pages without expiration date. However, for historical reasons, search engines should also interpret other date formats where possible and should be prepared to find values such as "", "0", "no" and "never". Such non-date values are to be interpreted as no expiration date.

Correctly formatted example:

<meta name='expires' content='2012-12-31T23:59Z'>

This tag is not to be confused with and has a different meaning than meta http-equiv='expires'.

Authoring web sites to use resolution independent images that display beautifully on high-resolution displays should be made as easy as possible for developers and should not require JavaScript to accomplish.

To accomplish this, I propose a new HTML Meta Tag, resolutions, that can be used to specify that high-resolution versions of images linked to from the page are available and that the browser should use them in place of the lower-resolution default images if it detects that a user is using a high-resolution screen. The resolutions meta tag lists the device-pixel ratios supported by images in the page.

So, for example…

<meta name="resolutions" content="2x">

… means that the developer is telling the browser that she has created 2x resolution images for the images linked to from the current page and named them with a @2x suffix.

To illustrate, if her image tag is as follows…

<img src="/images/flower.jpg" alt="A flower">

… then she has two image files under /images: the low-resolution default (flower.jpg), and a higher-resolution (200%) version named flower@2x.jpg.

(This is the same naming convention already used by Apple in its Cocoa Touch framework for automatically loading in higher-resolution versions of images.)

Based on the meta tag, if the browser detects that the user is running at a min-device-pixel-ratio of 2.0, it will automatically ask for the 2x version of the image (flower@2x.jpg) instead of the default image as specified in the image tag.

Finally, so as not to flood external sites with high-resolution image requests, this functionality would only work for local images specified via relative links.

Multiple resolutions

The resolutions tag can also contain a list of supported device-pixel ratios so as to support even higher-resolution displays when and if they become available in the future.

For example:

<meta name="resolutions" content="2x, 4x, 8x">

In this case, the developer would provide 2x, 4x, and 8x versions of all images. So, in the running example, she would make flower.jpg, flower@2x.jpg, flower@4x.jpg, and flower@8x.jpg.

Advantages

The advantages of this approach are several:

Makes it very simple for developers to support high-resolution displays like the iPhone 4's Retina screen

Does not require JavaScript

Does not change the default way that things work (if the meta tag is not specified, the browser simply behaves as it always has).

Failed Proposals

This doesn't actually work; use HTTP headers instead.Value must be "public", "private", or "no-cache". Intended as a simple way to tell user agents whether to store a copy of the document or not. An alternate for HTTP/1.1's cache-control; for publishers without access to modifying cache-control.

none

Unendorsed

DC.

Dublin Core, maintained by Dublin Core MetaData Initiative (DCMI), is an extensive system with some overlap with non-DC names.This reserves all strings that begin with DC and a dot. Not true; DC-HTML doesn't use hardwired prefixes, but defines the prefixes using link/@rel="scheme.prefix"

HTML5 prohibits URL-valued meta names. They should be rel keywords instead.Intended to reference legal policy of web site indicating that harvesting of e-mail addresses on the site is not permitted and in violation of applicable laws such as the CAN-SPAM Act of 2003.